Effect of temperature on excitation energy transfer and upconversion phenomena in Er : YVO4 single crystals

Investigation of excitation and decay of Er3+ in YVO4 single crystals has b een carried out at temperature range from 5 to 500 K. In the limit of low E r3+ content, the temperature dependence of the S-4(3/2) decay is not consis tent with predictions of multiphonon relaxation model. In heavily doped cry stals the 4S(3/2) decay is governed by cross relaxation process, whose rate grows steadily with increasing temperature. An efficient upconverted lumin escence near 550 nm following a cw and short pulse (5 ns) excitation of the I-4(9/2) level in the system under study has been recorded and analysed. C ontribution of the excited state absorption to these phenomena has been con sidered. (C) 2001 Elsevier Science B.V. All rights reserved.